Apparatus for treating plastic material



Feb. 25, 1936. H. D. STEVENS v APPARATUS FOR TREATING PLASTIC MATERIAL 2Sheets-Sheet 1 1' race D Siemens (lttornegs Feh 25, 1936. H. D. STEVENSAPPARATUS FOR TREATING PLASTIC MATERIAL 2 Shecs-Sheet 2 Filed April 10,1933 3rmentor Horace D. Sievens (lttornegS itself in folds upon thesurface of the rotating Patented Feb. 25, 1936 UNITED STATES PATENTOFFICE APPARATUS FOR TREATING PLASTIC E Firestone Tire & Rubber Company,Akron,

Ohio, a corporation of Ohio Application April 10, 1933, Serial No.665,308

10 Claims.

This invention relates to apparatus for treating plastic material, andmore especially it relates to rubber-working apparatus, such as mixingmills and warming mills, comprising automatically operating mechanismfor stripping the plastic sheet of material from one of the mill rollsand feeding it back into the bite of the rolls, whereby a more intimatemixing of the material is effected, or the warming thereof expedited.

The chief objects of the invention are to provide, in a rubber-workingmill, improved mechanism for stripping the plastic rubber compositionfrom a mill roll and then feeding it back into the bite of the millrolls. Another object is to devise mechanical rubber-mixing apparatuswhich will mix the rubber more thoroughly and uniformly than the manualmethod. A more specific object is to provide for so moving thework-stripping member relatively of the mill roll that improvedoperation is achieved. A further object is to provide a single memberfor scraping rubber composition from a mill roll and feeding it backinto the mill, which scraper may be movable longitudinally of a millroll in both directions, and operably engage said roll while moving inboth directions. Other objects will be manifest.

The foregoing and other objects are achieved in the present inventionwhich comprises broadly a two-roll mill, a work-scraper adapted toengage the. surface of one of the mill rolls, and means for moving thescraper relatively of the mill roll in a determinate course whichcomprises first moving the scraper into engagement with the mill roll ata point near but spaced from one end of the roll, then moving it to thenear end of the roll, thenreversing its course and moving it toward theopposite end of the roll, and then removing it from the'roll before theopposite end is reached, all of said movements occurring in a planeparallel to the axis of the mill roll. The initial movement of thescraper toward the end of the roll is of sufiicient duration and extentto permit the scraper completely to penetrate the thick sheet of plasticmaterial thereon, so that the reverse movement of the scraperprogressively scrapes and strips the material from the roll from one endthereof toward the other end, the stipped material rolling upon itselfor arranging roll, and then passing endwise into the bite of the rollsafter the scraper is lifted, at the conclusion of the cycle ofoperation, near the opposite end of the roll. The operation described iscontinu ous, and is repeated, first at one end of the mill roll and thenat the other end.

Of the accompanying drawings:

Figure 1 is a front elevation of apparatus embodying the invention, inits preferred form;

Figure 2 is a section on the line 22 of Figure 1, showing a roll-scraperdevice in side elevation;

Figure 3 is a diagrammatic view showing the course of the scraper withrelation to a mill roll;

Figure 4 is detail elevation of a mill roll showing the scraper as itinitially engages the same;

Figure 5 is a view similar to Figure 4 showing the scraper at theposition where its direction of movement on the mill roll is reversed;and

Figure 6 is a view similar to Figures 4 and 5 showing the extremeposition of the scraper before it moves out of engagement with the millroll. 7

Referring to Figures 1 and 2 of the drawings, there is shown arubber-working mill comprising end-frames ID, ID in which are journaleda pair of laterally disposed, horizontal rolls II, l2, that are gearedtogether as by gears such as that shown at l3, Figure 1, and driven inunison by the usual driving means (not shown). The rolls H, [2 areadapted to form a sheet Id of plastic composition from a bank l5 of suchcomposition that is fed into the bite between said rolls, the sheet l4being shown herein as being formed on the front roll [2.

Mounted upon the top of end frames ID are respective brackets 16, I 1that carry a pair of guide-bars I 8, I9 that are parallel to each otherand to roll l2 and are disposed in a vertical plane with the latter. Theguide-bars l8, l9 slidably support a carriage 20 that is movablelongitudinally thereof, and the front face of said carriage is formedwith a vertical dove-tail slideway 2| in which is mounted a slide 22.Vertical movement of the slide 22 is effected by means of a superposedvertically positioned, double-acting, fluid-pressure operated cylinder23 that is carried by a bracket 24 that is mounted upon the carriage 20,the piston rod 25 of cylinder 23 ex tending downwardly and having itsouter end connected to the upper end of said slide. Fluid pressure issupplied to the upper and lower ends of cylinder 23 through flexiblehose or pipes 26, 2'! respectively, that constitute extensions of re=spective rigid pipes 28, 29 that are connected to a control valve 30,the latter being provided with a supply pipe 3| extending to anysuitable source of pressure fluid (not shown), and with the usualexhaust port (not shown).

A light frame 32 may be provided for supporting the carriage 26longitudinally of t'ne guide-bars" I8, l9, whereby the scraper 36ismovedglongitudinally of roll l2, there is provided an endless sprocketchain 38 that is trained about a pair of sprockets 39, 40 positioned atopp'osi-teend's ofthe mill. As is most clearly shown in Figure 1, thesprocket 39 is mounted upon an idler shaft 4| that is journaled in abearing bracket 42; thei latter being mounted upon a lateral extension43 of. the bracket [6. An adjusting screw 44 is threaded through bracket['5 and engages bracket 42 for the purpose of tightening; or looseningsprocket chain 38. The? sprocket lfi is mounted upon" a. driven shaft 45that is journaled inra laterallyextending bearing structure lli formedon: the

bracket l:'s',i Bothends of shaft 45: extend beyond saidbearingstructure and-one-endithereof carries asprocketfl thatis-connected by'a sprocket chain 43 toa sprocket on shaft 5&0); areduc-- tion gear device 5i, the latter being driven bya sprocket chain52 connected to'a reversibie mo tor 53;. Thermotor53and.reduetionrgeamdevice5I are mounted upon a framework 54- carried1byone of the end: frames at ofJthemil-l; :Thecarriage 26 is connected: tosprocket chain: 38 by means of" a plate: 55 that .has'i-ts lower marginformed with. a

plurality of teeth, such asthe-tooth 56-, Figure 2, which teeth extendthrough respective links of said sprocket 'chain andabut a retainingplate 51, both plates 55- and 51 being secured tothe rear face ofcarriage 2D:

The arrangement issuchvthat the carriage 201's propelled longitudinallycf the guide-bars l8-, 9 when thereversiblemotorr53is drivenr Thedirection of rotation at the motor5 -3'is controlledby respectivereversing switches 59,6!) that are. 'mounted upon the. tops ct bracketsI6, l-l, each of said switches being: provided with anoperating lever 6|extending toward. the carriage 20 'The latter is provided withadjustablegoppositely pro jecting fingers 62-, 62 adapted to-engage therespective switch levers 6! to operate switches 59 or 6!! whenever thecarriage 20 approaches the respective ends of guide-bars l8, l9; therebyreversing' motor 53 to cause: the carriage to move in the oppositedirection. Adjustable positive stops 6?, 63 are mounted upon guide-barl9 to prevent over-run of the carriage 20 in either direction.

The reciprocating movements of the carriage 20 along the guide-bar's;f9, and the up and down movements of. the slide 22 on? said carriageoccur in determinate timed relation to each other whereby the previouslydescribed movements of the scraper 36 with relation to the mill roll l2.

are'efiected- To this end'suitahle'means is provided for the operationof the valve3fl hereinbefore described,- said valve being mounted uponabracket'65. The specific form of the valve operating and timing: meansis not disclosed herein, however, as it forms no part of the presentinven-. tion. When the valve as is operated in one direction, fluidpressure passes from pipe 3f into pipe 29, thence tome lower end ofcylinder 23 to raise the scraper 36; When the. valve is operated intheopposite direction; the fluid pressure'pa'sses it is in position yion into pipe 28, thence to the upper end of cylinder 23 to lower thescraper 36. The various. movements of'the scraper 36 wit relation tomill roll l2 are diagrammatically illustrated in Figure 3. The courseshown in full lines and designated by characters 1), w, m, y and z is acomplete. cycle ofv operation at... one end. of the r 7 roll, andthecourse showr-r in brokemlines and des ignated v to z" inclusive, is acomplete cycle of operation at the other end of the roll, which bringsthe scraper back to the point of starting of the ihrstcyelei 'lheupwardly and downwardly moving phases of the scrapers movements, such asare indicated by lines o, w and y} z are necestinuously reciprocatedlongitudinally of roll it, by the motor 33pthen beingtm .thezbroken-;line. po-

sition I shown; ina 42; When: fluid. passes throughipi'pe; Zilfto thetop oficylinder'n. and'causes scraper 36 ta descendrinto engagement;with roll: H at point 10; Figures 3-andi4-,.the scraper 316: then movesfromv point. um to point. 3;. Figures 3:

and 5,. at which point switch 60;: operated. tor

reverse thedirectionfi of-longitudina'l-movement of carriage 201 Aftertherscraper traverses the: roll.

I! to position 1, the: valve: is operated to=;the-position' that admitsfluid pressure ti'iroughzpipe 2% to:

thelower end'ot cylinder 23-, andventsfluid from.

the top thereof} thus: causing "seraper .361 to rise The rising movementthe scraper-starts: when .udinally of roll 12,: and terminatesat-position s asis most clearly shown; in'Figures 3 and 6. The scraper36' remains in. raised position from point z. to point ucom.- pletes acycle of operation. oithe scraper on one end of rolll2:

Valve .30 is then operated: to reverse the pressure in cylinder 23 andthe scraper is again. lowered to initiate a cycle-v of; operation on.the

otherend of roll l2; which circleisldenticahwith the cycle justdescribed, and. is indicated Figure 3 by points 12." and 2: inclusive,the scraper. returning to the point of starting the first cycie.

It will be seen that the scraper. always fixedly positioned in" a planeparallel: to theaxisi of the roll l-Z, and-operates against the-roll thesame manner while moving in either direction. longitudinally thereof.-In each. case the. scraper,

after forcing and cutting its way through the sheet of material M duringits initial: downward and lateral movement toward one end of: the roll,

reverses its direction and moves the opposite end of the roll, forcingits way through the sheet M and piling it up somewhat atits leadingedge, as clearly shown in 1; andllaying the stripped materialinconvoluticns or folds that are disposed obliquely of the roll; Whenthescraper rises, the fold of scraped material passes substantiallylengthwise into the bite of rolls I. i, l: where by intimate mixing c-ithe ingredlentsthereof is What is claimed is:

1. In apparatus for treating plastic material, the combination of a millcomprising rolls for forming a thick sheet of the material on one of therolls thereof, a scraper movable longitudinally of said roll forremoving material therefrom, said scraper presenting a blunt leadingsurface to the material to cause the latter to pile up in front of saidsurface during the said movement of the scraper, and means for movingsaid scraper out of and into engagement with said mill roll at pointsintermediate the ends thereof.

2. In apparatus for treating plastic material,

the combination of a mill comprising rolls for forming a thick sheet ofthe material on one of the rolls thereof, a scraper for removingmaterial from said mill roll, and means for moving the scraperrelatively of the mill roll in the following course, to wit, moving itinto engagement with the roll at a point near but spaced from the end ofthe latter, moving it to the near end of the roll, reversing itsdirection and moving it toward the opposite end of the roll, and thenremoving it from the roll at a point somewhat short of said oppositeend.

3. In apparatus for treating plastic material, the combination of a millcomprising rolls for forming a sheet of material on one of the rollsthereof, a scraper for removing material from said mill roll, means forcontinuously moving said scraper from one end of said mill roll to theother, and means timed therewith for raising the scraper from andlowering it onto the mill roll, the scraper initially engaging the rollsomewhat before reaching the end thereof toward which it is moving.

4. In apparatus for treating plastic material, the combination of a millcomprising rolls for forming a sheet of material on one of the rollsthereof, a scraper for removing material from said mill roll, means forcontinuously moving said scraper from one end of said mill roll to theother and back again, and a pressure cylinder timed with said lastmentioned means for moving the scraper into and out of engagement withthe mill roll.

5. In apparatus of the character described, the combination of a pair ofdriven mill rolls, a scraper consisting of a flat blade rigidlysupported in a plane parallel to the axis of said mill rolls and havinga margin of substantial length positionable flush with the surface ofone of said rolls, and means for moving said scraper, in said plane, inopposite directions in engagement with one of said mill rolls.

6. In apparatus of the character described, the combination of a pair ofdriven mill rolls, a scraper comprising a rectangular blade disposed ina plane parallel to the axis of said mill rolls and adapted to bebrought into engagement with one of said rolls, said blade having bluntend portions rising from the surface of said mill roll when said bladeis in engagement therewith, and means for moving said scraper inopposite directions in its own plane, longitudinally of said mill roll,whereby said scraper may remove a portion of a sheet of material on saidmill roll and one of said end portions will move into engagement withthe portion of the sheet of material so removed from the roll forgathering or rolling said material upon itself preparatory to feedingthe material back in between the mill rolls, and upon movement of thescraper in the opposite direction, the other end portion of said scraperwill engage the material removed from the mill roll for the purposespecified.

7. In apparatus for treating plastic material, the combination of a millcomprising driven rolls for forming a sheet of the material on one ofthe rolls thereof, a scraper for removing material from said mill roll,means for moving said scraper into engagement with the surface of oneend portion of said mill roll by cutting through the material on saidend portion, means for moving said scraper along said mill roll towardthe middle thereof for progressively cutting and rolling said materialupon itself and piling it up in front of the leading edge of thescraper, and means for withdrawing said scraper from said mill rollintermediate the ends thereof to permit the rolled material to be drawnback between said driven rolls, said scraper and said means beingconstructed and arranged to operate in like manner from the opposite endportion of said mill roll.

8. In apparatus of the character described, the combination of a millhaving cooperating rolls and means for rotating the same adapted to forma sheet of plastic material on one of said rolls, and a scraper movablelongitudinally of the said roll in contact therewith to remove materialtherefrom, said scraper presenting a blunt leading surface to thematerial on the roll so as to pile up material in front of said leadingsurface.

9. A mill for plastic material having cooperating rolls and means forrotating said rolls, in combination with a fiat rectangular blade, andmeans for moving said blade longitudinally of one of said rolls with onemargin of the blade flush with the surface of said roll, the adjacentleading margin of the blade being blunt to pile up the material in frontof it.

10. A mill for plastic material having cooperating rolls and means forrotating said rolls to form a sleeve of plastic material on one of them,in combination with a rectangular scraper having a cutting edge andadjacent blunt edges, means for moving said scraper toward a mill rollwith its cutting edge foremost so as to penetrate the material on saidroll, and means for moving the scraper laterally, longitudinally of theroll, to strip material from the roll by piling it up in front of theleading edge of the scraper.

HORACE D. STEVENS.

